Hi, sorry to say this again but the question is unclear. For example what is meant by "the value does not store into the text area", how are you trying to store it and what error do you get? Not sure if anyone can help you with a solution if you don't express your question in enough detail.

here are the 3 images for better understanding

the first image is my codes

the 2nd is my first process

the 3rd is the subform loading the previous process. but no duration of travel

In line 10 of your code, you are pointing to a input field named "days". Is "Duration of Travel" field having such name too?

yes.

I have the same problem as Jedi has mentioned. The "Duration of Travel" field is show the total number in the form. 

But when I create datalist which included the field "Duration of Travel".  I got not luck to show the number